JetBrains Rider 2017.2 Help

Keymap:

Code Inspection: Access to disposed closure

First of all, let's make sure that you understand what a closure is. To put it simply, a closure in C# is a lambda expression or an anonymous method that captures some variables from an outer scope. Here is the simplest example:

// A self-contained lambda. Not a closure.ActionprintOne=()=>{Console.WriteLine("one");};// A closure - a lambda that captures a variable from an outer scope.stringmyStr="one";Actionprint=()=>{Console.WriteLine(myStr);};

In the example above, print will capture the variable myStr (and not it's value) and will only get the value of myStr when you invoke print().

In more complex scenarios, when a closure is defined in a changing context, it may not behave as expected.

One of the situations where it may happen is a closure defined inside a using statement:

In the above code, JetBrains Rider issues the Access to disposed closure warning for writer.Write(text);. The reason for that is ExecuteDelayed() could execute the lambda after the writer's scope is disposed, which will result in a runtime exception.